Bates et al. U.S. Pat. No. 7,245,789 is incorporated by reference herein in its entirety, including its discussion of systems and methods for minimally-invasive optical-acoustic imaging. It discusses, among other things, an imaging guidewire that includes one or more optical fibers communicating light along the guidewire. At or near a distal end of the guidewire, light is directed to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound energy is sensed by an ultrasound-to-optical transducer. A responsive signal is optically communicated to the proximal end of the guidewire, such that it can be processed to develop a 2D or 3D image.